Objective To explore the classification system and outcomes of surgical treatment for terrible triad of the elbow.Methods Data of 42 patients with terrible triad elbow injuries who were surgically treated between 2009 and 2015 were retrospectively analyzed.There were 29 males and 13 females with a mean age of 47 years at the time of injury.42 patients of terrible triad injuries were classified into four types:type ⅠA,ⅠB,Ⅱ,Ⅲ,and Ⅳ injuries.Type ⅠA and Ⅱ injuries were treated through an isolated lateral approach,while type ⅠB,Ⅲ and Ⅳ injuries were treated by a combined lateral and anteromedial approach.Operative treatment consisted of repair or replacement of the radial head,repair of the lateral collateral ligament (LCL) and coronoid fracture fixation.Type ⅠA injuries were treated with radial head and LCL repair without coronoid fixation.Type Ⅳ elbow injuries were treated with medial collateral ligament (MCL) repair.Elbow functional status was evaluated using the Mayo elbow performance score (MEPS).Results There were three patients with type ⅠA injuries,7 patients type ⅠB injuries,15 type Ⅱ injuries,10 type Ⅲ injuries,and 7 type Ⅳ injuries.The average follow-up period was 30 months (range,24-56 months).All fractures of coronoid got union at average 11.5 months except for type ⅠA injuries.40 patients with fractures of radial head got union at average 12.4 months and two patients underwent radial head replacement without loosening.The mean flexion-extension arc was 107°±22°,the mean flexion contracture was 20°±10° and the mean flexion was 127°±14°.The average forearm rotation arc was 145°±14°,which included an average pronation of 73°±8° and an average supination of 71°±9°.The mean MEPS was 89±9 points (range,55-100 points),with excellent results in 24 elbows,good result in 17 and poor result in one;the excellence rate was 97％ (41/42).Thirteen patients had radiographic signs of arthrosis according to the Broberg-Morrey system (9 elbows were grade 1 and 4 were grade 2).5 patients had evidence of heterotopic ossification,of which four had minimal periarticular ossification and did not require additional surgery.The remaining patient showed significant heterotopic ossification and required an elbow release.1 patient with type Ⅲ injury developed transient median nerve paralysis and got full recovery after conservative treatment for 8 weeks.1 patient with type Ⅲ injury developed ulnar neuropathy and required an anterior ulnar nerve transposition.2 patients,who had shifting hardware but still achieved union,required a second surgery to remove the implant:one patient had a Kirschner wire shift from the radial head at 6 months after surgery,and the other had a loose screw in the coronoid process at one year after surgery.Conclusion Our classification system of terrible triad of the elbow may provide a guide for the selection of an ideal surgical approach and treatment modality.